Characterization of triplet separation and diffusion in amorphous pentacene films via ultrafast infrared spectroscopy

The performance of photovoltaic and light-emitting devices that utilize singlet fission sensitization has been modest to date, despite spectroscopic measurements reporting high triplet exciton multiplication yields in the singlet fission active layer of these devices. This contrast highlights the need to characterize the factors that underpin device performance, such as triplet separation and diffusion. Here, we use ultrafast infrared spectroscopy to probe the dynamics and separation of correlated triplet pair intermediates following singlet fission in amorphous and crystalline pentacene films. The ultrafast vibrational measurements reveal that triplet-pair separation occurs on similar timescales in both types of films, despite differences in intermolecular coupling strength. Conversely, ultrafast electronic spectroscopy measurements of diffusion-controlled triplet-Triplet annihilation reveal that triplet diffusion in the amorphous film is an order of magnitude lower than the crystalline analog. Together, these results suggest that sparse triplet traps limit the transport of triplet excitons in the amorphous film. Therefore, device developers should seek to identify the structural origins of these states to identify molecular structures that self-Assemble in patterns that avoid triplet trap state formation.

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Work Title Characterization of triplet separation and diffusion in amorphous pentacene films via ultrafast infrared spectroscopy
Access
Open Access
Creators
  1. Kyle T. Munson
  2. John B. Asbury
Keyword
  1. Singlet fission
  2. Vibrational spectroscopy
  3. Transient absorption
  4. Excitons
  5. Triplet transport
License In Copyright (Rights Reserved)
Work Type Conference Proceeding
Publisher
  1. Proceedings Volume 11799, Physical Chemistry of Semiconductor Materials and Interfaces XX, 117990B
Publication Date August 26, 2021
Publisher Identifier (DOI)
  1. https://doi.org/10.1117/12.2594600
Source
  1. SPIE Nanoscience + Engineering, 2021, San Diego, California, United States
Deposited January 30, 2023

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Version 1
published

  • Created
  • Added JPCA_Singlet_Fission_Amorphous_Paper_Resubmitted.pdf
  • Added Creator Kyle T. Munson
  • Added Creator John B. Asbury
  • Published
  • Updated Source, Keyword, Publisher, and 1 more Show Changes
    Source
    • SPIE Nanoscience + Engineering, 2021, San Diego, California, United States
    Keyword
    • Singlet fission, Vibrational spectroscopy, Transient absorption, Excitons, Triplet transport
    Publisher
    • The Journal of Physical Chemistry C
    • Proceedings Volume 11799, Physical Chemistry of Semiconductor Materials and Interfaces XX, 117990B
    Publication Date
    • 2020-10-14
    • 2021-08-26
  • Deleted JPCA_Singlet_Fission_Amorphous_Paper_Resubmitted.pdf
  • Added SPIE Conference Paper 2021.pdf
  • Updated